1. SECTIONS:
2. preface & acknowledgements
3. genetics at a glance
4. contacts, support & testing
5. testing & pregnancy
6. newborn screening
7. cancer in the family
8. cardiovascular conditions
9. chromosomal conditions
10. clotting & bleeding conditions
11. cystic fibrosis
12. diabetes
13. fragile X syndrome and other causes of developmental delay
14. haemoglobinopathies
15. hereditary haemochromatosis
16. neurofibromatosis
17. neurological conditions
18. psychiatric conditions
19. genetics in practice
20. emerging genetic technologies
21. glossary

Cardiomyopathies

 

(a) Familial hypertrophic cardiomyopathy (FHCM)

 

Clinical features

1. Hypertrophic cardiomyopathy (HCM) is a primary cardiac disorder characterised by hypertrophy, usually
   of the left ventricle.
2. The clinical presentation of HCM can vary from minimal or no symptoms with an asymptomatic course, to the development of serious complications including heart failure and sudden death.
3. Symptoms may include:
4. Chest pain
5. Symptoms related to pulmonary congestion
6. Impaired consciousness

 

Genetics

1. Most cases of HCM are hereditary with the most common form of inheritance being autosomal dominant.
2. There is considerable genetic heterogeneity in FHCM.
3. There are at least ten genes associated with FHCM.
4. The most common set of genes are those that code for various components of the cardiac sarcomere.
5. There is also considerable variability in the clinical impact of different gene mutations within the same gene and also between individuals with the same mutation.

 

Prevalence

1. FHCM is estimated to affect 1 in 500 in the Australian population.
2. In 5% of individuals who are found to have causative gene mutations, multiple mutations (eg two different mutations in the same gene compound heterozygotes, or mutations in two different genes – double heterozygotes) are found.
3. Current data suggests that these individuals have a more severe phenotype compared to individuals who are heterozygous or in whom no gene mutation has been identified.

 

Investigations

1. 1° relatives of affected individuals should have regular cardiac screening including investigations such as echocardiography and ECG.
2. The suggested time intervals for clinical screening of unaffected at-risk family members should follow the intervals outlined in Table 2.
3. Affected individuals will require regular cardiac investigations and monitoring of symptoms.
4. Genetic testing is currently available in commercial laboratories overseas, although it is likely that genetic testing will become available in Australia in the future.

 

Table 2

Recommended frequency of clinical screening for unaffected family members

 

Management

1. The clinical management of HCM is complex in part due to the heterogeneous symptoms exhibited by affected individuals as well as the marked variability in the natural history of the disease. Many treatment options are available to HCM patients including:
2. Lifestyle modifications, eg avoiding competitive sports (in all patients with HCM)
3. Use of pharmacological agents, eg calcium channel blockers, beta blockers, and diuretics
4. For those with significant left ventricular outflow tract obstruction with symptoms unresponsive to drug therapy, surgical intervention may be indicated
5. The use of ischaemic cardiomyopathy (ICM) therapy in the prevention of sudden death

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